The present invention relates to a private branch exchange (PBX) system, and more particularly to a method and device for maintaining the PBX system by establishing a data communication path between a remote maintenance center and the PBX system through a public switching telephone network (PSTN).
With reference to FIG. 1, a central processing unit (hereinafter called as CPU) 101 controls an overall operation of the PBX system so as to perform a variety of functions and establish a speech path.
A memory 102 comprises a ROM for storing a program and initial service data to generate a basic call and perform all kinds of functions of the PBX system and a RAM for storing temporarily data generated while performing the program under control of the CPU 101.
An interface circuit 103 is connected between the CPU 101 and various structural elements of the PBX system and interfaces all kinds of signals and data generated while performing an exchange function of the PBX system. A switch circuit 104 exchanges all kinds of tone signals, dialing data and voice data through a channel designated by a control of the CPU.
An extension circuit 105 is connected between the switch circuit 104 and a subscriber telephone set 111, establishes an extension speech loop under a control of the CPU 101, supplies an electric current to the telephone set 111, and interfaces all kinds of state signals and voice signals between the switch circuit 104 and the subscriber telephone 111 or 111'.
A general office line circuit 106 is connected between the switch circuit 104 and the PSTN, establishes an office line speech loop by seizing an office line under a control of the CPU 101, transmits all kinds of state signals and voice signals received from the office line to the switch circuit 104, and in turn transmits the voice signal and state signal from the switch circuit 104 to the office line.
A DID (Direct Inward Dialing) office line circuit 107 is connected between the switch circuit 104 and the PSTN, connects a call signal to the subscriber 111 directly according to a dialing signal from the office line by seizing a DID trunk under a control of the CPU 101, and interfaces all kinds of signals and voice signals between the DID trunk and the switch circuit 104.
A DTMF (Dual Tone Multi Frequency) reception circuit 108 is connected to the switch circuit 104, converts a received dialing signal into a digital data and transmits it to the CPU 101. A tone generating circuit 109 is connected to the switch circuit 104 and transmits a designated tone signal to the switch circuit 104 under a control of the CPU 101. An input/output circuit 110 is connected to an external terminal 112 and printer 113 and interfaces data between the external terminal and the PBX system under the CPU 101.
A key telephone system may be used in place of the PBX system as described in the above statement.
Generally a function of maintaining the PBX system is performed by utilizing the telephone set 111 or the terminal 112. If an abnormal state occurs on the PBX system or changing information of the subscriber is required, it is possible to check the abnormal state or change the information of the subscriber by utilizing the telephone set 111 or the terminal 112.
But it is difficult for a system operator or an user to maintain and administrate the PBX system by themselves because an operation of the PBX system is complicated and varied. Accordingly, a technician from the maintenance center must visit a site of the PBX system, in order to inspect the abnormal state and add or delete a function requested by an user.
However it is difficult to satisfy an user's requirement promptly because the technician has to visit the site of the PBX system for maintaining directly, and also it takes much time to maintain because of the abnormal state being inspected on the spot. Furthermore an efficiency of the PBX system is decreased because an operation of the system may be impossible during the maintaining of the PBX system. And the maintenance center should employ a great number of maintenance workers for satisfying various users' requirements.